The present invention relates to a conveyor and more particularly to a low profile system for material transfer which avoids the numerous problems inherent in similarly employed prior art devices.
Various prior art conveyor systems have been developed and proposed to take up the slack in a conveyor belt. Often the conveyor belt expands due to stress under normal conditions of usage. Furthermore, the belt may become loose due to change in temperature or humidity in the immediate environment. Various prior art devices have attempted to solve this problem using a spring loaded idler roller. U.S. Pat. No. 2,955,701 to Schwertl is typical of such prior art devices. This patent employs a spring loaded roller at the end of the conveyor belt. Such devices, however, cause a change in the linear distance from one end of the conveyor system to the other in proportion to the movement of the spring. This variation in the effective length of the system renders it impractical to utilize such systems to interface with other stationary equipment at either end of the module.
Various prior art devices have attempted to achieve compactness and low profile. U.S. Pat. No. 2,523,829 to Hubbell is typical of such prior art devices. The Hubbell patent discloses a low profile module. Such devices however fail to disclose the utilization of the vertical sidewalls of the frame for guidance of the conveyor belt in the forward and reverse direction to prevent lateral shifting of the conveyor belt.
Another problem inherent in prior art conveyor modules is the inaccessibility to the apparatus and particularly the idlers within the frame. Often it is necessary to obtain access to the apparatus within the frame for purposes of threading the belt, repairing the apparatus and routine maintenance. It is therefore important to be able to obtain ease of access to the apparatus. U.S. Pat. No. 3,120,303 to Leonard discloses conveyor sections which provide access to the apparatus within the frame. Such devices however require a substantial amount of disassembly. Furthermore, the guide rails of the frames of such devices do not provide sufficient guidance to prevent lateral shifting of the belt.
Various prior art conveyor systems require a number of bearings coupled to the rollers particularly the drive rollers. U.S. Pat. No. 1,943,998 to Adams is typical of such prior art devices. These devices require two or more bearings coupled to the rollers shown therein. It has been found desirable to eliminate one of the roller bearings and couple the drive motor directly to the drive roller.
In order to increase the friction between various rollers in the conveyor belt in typical prior art devices, an assembly including a number of rollers has been employed to cause the belt to contact one of the rollers for a substantial part of its circumference. Such devices however have not been used to their optimum capacity since typically they do not increase the contact by the belt with a substantial portion of the circumference of the drive roller.